Electrical air heater



NOV. 27, 1934. A J KERCHER ELECTRICAL AIR HEATER Filed Jan. 19, 1931 4Sheets-Sheet 2 A INVETOR. flew/0e J (fine :2 025;; QXZZA%% ATTORNEYS.

NOV. 27, 1934. J KERCHER 1,982,139

ELECTRICAL AIR HEATER Filed Jan. 19, 1931 4 Sheets-Sheet 3 I I 67 I.INVEIEVITOR. fir/rue J/Q'Ic/nse 76 WW M 77 I ATTORNEYS.

Nov. 27, 1934.

A. J. KERCHER 1,982,139

ELECTRICAL AIR HEATER Filed Jan. 19, 1951 4 Sheets-Sheet 4 www/w ATTORNEYS.

Patented Nov. 27, 1934 PATENT orrlcs ELECTRICAL an; HEATER Arthur J.Ker-char, Berkeley. Calif.

Application January 19,

13 Claim.

This invention relates generally to electrical appliances adaptedparticularly for the heating of rooms of dwellings and other buildings.It relates particularly to that type of electrical air heaters in whicha relatively large proportion of the heat developed by the electricalresistance or heating elements is imparted to circulative currents ofair.

General objects of the invention arez-To de- '10 vise an electrical airheater of the above type which will be relatively compact compared toits heating capacity; which will provide for relatively rapidcirculation of air in the room thru the heater housing; which will be ofrelatively high efliciency; and which will operate in such a manner asto maintain the walls of the heater housing at a relatively low safetemperature.

Further objects of the invention will appear from the followingdescription in which certain preferred embodiments of the invention havebeen set forth in detail in conjunction with the accompanying drawings.It is to be understood that the appended claims are to be accorded arange of equivalents consistent with the state of the prior art.

Referring to the drawings:

Figure l is a front view of an electrical air heater of the wall recesstype, incorporating the present invention.

Fig. 2 is a cross sectional view taken along the line 22 of Fig. 1.

Fig. 3 is a front view of an electrical air heater of the wall hang ontype incorporating the invention.

Fig. 4 is a cross sectional detail taken along the line 44 of Fig. 3.

Fig. 5 is a front view of a portable type electrlcal air heaterincorporating the present invention.

Fig. 6 is a cross sectional detail taken along the line 66 of Fig. 5

Fig. 7 is a cross sectional detail of 'a wall recess type of electricalair heater incorporating the invention, and illustrating a modificationof the general type of heater illustrated in Figs. 1 and 2.

Figs. 8, 9 and 10 are circuit diagrams illustrating electrical circuitconnections which can be utilized with the invention.

Before explaining in detail the various forms of the inventionillustrated in the drawings. it may be stated that in my invention amotor driven fan mounted within the heater housing is utilized foraccelerating, inducing or forcing a rapid flow of air thru the heaterhousing. While fans or blowers have previously been utilized in connec-1931, Serial No. 509,747

tion with electrical air heaters, in my invention the heater structureis characterized by the fact that the currents of air flowing thru theheater housing are divided into primary and secondary currents, thesecurrents being substantially isolated by the provision of separate airflow passages. As will be presently explained the primary air currentsarepreferably made relatively rapid by the action. of the fan or blower,and effect major heating of the air within a room, while the secondaryair currents form the useful purpose of maintaining certain walls of theheater housing at a relatively low safe temperature.

Referring to that form of the invention illustrated in Figs. 1 and 2,there is shown a housing 10 preferably made of metal, and includingrelatively upright back and side walls 11 and 12, a bottom wall 13, anda forwardly inclined top wall 14. The front of this housing is coveredby a perforate wall or grille 16 which is suitably secured to theremainder of the housing. The housing is adapted to be positioned withina wall recess 17, whereby the grille 16 is substantially flush with theforward surface of the wall.

Mounted within housing 10 in a manner to be presently described, thereis a suitable electrical motor 19. Mounted upon the shaft of this motorthere is a rotatable fan or blower impeller 21. Surrounding impeller 21there is a casing 22 which forms what can be termed a primary passagefor circulation or flow of primary currents of air. The preferred formfor casing 22 is apparent from an examination of Figs. 1 and 2. It willbe noted that the back wall 23 of the casing extends in a planesubstantially at right angles to the axis of rotation of impeller 21,and between this impeller and the back wall 11 of the housing. Fheforward wall 24 of casing 22 extends parallel to wall 23, and adjacentthe inner surface of grille 16. The upper portion of wall 23 merges witha forwardly curved upper wall 26. The side walls 2'7 of the casing arecurved as shown in Fig. 1, and extend between the edges of walls 23 and24. The upper edge of wall 24 terminates short of the upper edge of wall26, thereby forming a discharge opening 28 (Fig. 1). This opening 28 isrelatively elongated by virtue of the fact that side walls 27 divergeupwardly, and extends across the upper portion of grille 16, whereby airdelivered outwardly thru casing 22 is discharged outwardly thru theregistering grille openings. Suitable openings are also provided incasing 22 for the inflow of air. Thus wall 24 is shown provided with anopening 31 which is substantially in alinement with the axis of rotationof impeller 21, and

which is in registry with certain of the more central openings in grille24 as shown in Fig. 1. Another inflow opening 32 is in wall 23 andsurrounds the motor 19.

To convey air to opening 32 in casing 22, an air flow conduit 33 isprovided immediately below casing 22. This conduit 33 can be formed byrelatively upright wall 34 which merges with a forwardly curved lowerwall 36. Side walls 3'7 extend between the edges of walls 34 and 36 andthe adjacent walls of casing 22. By virtue of the downwardly divergingcharacter of walls 3'7 as shown in Fig. 1, the lower open end 38 ofconduit 33 is relatively elongated as shown in Fig. 1, and is inregistry with openings in the lower portion of the grille 16. The innerand upper end of conduit 33 delivers. the air about motor 19 and thruopening 32 to casing 22. Motor 19 can be conveniently mounted within ashell 41 which in turn is mounted upon wall 34. The inner edge portionof shell 21 can be provided with a flared portion 42 to more eflicientlydirect air flow.

With the above described structure, it will be noted that upon operationof impeller 21, air will be drawn in thru the lower portion of grille16, thru conduit 33, opening 32, and will be delivered by the impellerthru discharge opening 28 and openings in the upper portion of thegrille. By virtue of the function of opening 28 to discharge air fromcasing 22 thru the grille and from the upper portion of the housing, theupper portion 43 of casing 22 can be designated generally a dischargeportion. As representative of suitable electrical means for heating theair caused to flow by operation of impeller 21, there is shown aplurality of coil resistance wires 44 carried by suitable supportbrackets 46, and arranged to surround the periphery of impeller 21.

To secure certain advantages, as for example ease of manufacture and tofacilitate making repairs, the structure forming casing 22 and conduit33, is mounted upon and carried as a unit by grille 16 as shown in Fig.2. From an inspection of Figs. 1 and 2, it will also be noted that thisentire structure when in operative position is retained in spacedrelationship with respect to the back, sides, top and bottom walls ofthe housing 10. The space thus formed, indicated generally at 4'7 inFig. 2, forms an upstanding flue for passage of convection currents ofair. It will be noted that the lower end of this flue is incommunication with the exterior of the housing thru openings along thelower edge of grille 16, below wall 36, and that likewise the upper endof flue 4'7 is in communication with the exterior of the housing thruopenings along the upper edge of grille 16 above wall 26. Likewise theflue or above mentioned space is in communication with the exterior ofthe housing'at both sides of the heated housing, thru the openings alongthe side edges of grille 16.

In operating the heater described above, assuming that current issupplied to the elements 44 and to the electrical motor 19, a rapid flowof air will occur thru casing 22 by virtue of rotation of impeller 21.into the lower portion of the housing thru opening 38, and after beingheated by contact with elements 44, the air is discharged in a generallyhorizontal direction from the upper portion of the heater housing thruopening 28. By virtue of proximity with elements 44, and also by virtueof contact with the heated currents of air, the walls of casing 22 willbecome heated to an elevated temperature, and a large part of this heatThe circulation of air is will be transmitted to air present in spaceflue 47. Thus an upwardly moving current of air is induced to flow thruthis flue, the air currents flowing inwardly into the lower portion ofthe housing, and outwardly thru grille 16 abcve wall 26. Such a flow ofconvection currents of air serves to carry away heat transmitted to thewalls of casing 22, to effectively deliver this heat to the air withinthe room, and at the same time the back, sides, top and bottom walls ofhousing 11 are maintained at a relatively low safe temperature. 'Even inthe event that motor 19 fails to operate, suflicient heat will becarried away by such'convection currents of air to prevent a firehazard. In explanation of the appended claims it may be noted thatcasing 22 together with conduit 33 can be considered as forming aprimary passage, while space or-flue 4'7 can be considered as forming asecondary passage for air flow thru the heater housing.

That form of the invention illustrated in Figs. 3 and 4 is somewhatsimilar to the modification described above with referenceto Figs. 1 and2, except in this instance the heater is of such a form that it isadapted for hanging flat upon the wall of a room. Thus the housing inthis instance is formed by a relatively flat back wall 51, together witha forwardly bulged front plate or wall 52. Air flow casing 53,corresponding to casing 22 of Figs. 1 and 2, is mounted upon the frontwall 52, between this wall and back wall 51. Inflow and outflow openings54 and 56 are formed in front wall 52, and therefore a wallcorresponding to wall 24 of Figs. 1 and 2' can be omitted. Conduit 5'7corresponding to conduit 33 of Fig. 2, communicates with the lower rowof openings 58 in plate 52. A row of openings 59 in the lower portion ofplate 52, below openings 58, and a row of openings 61 in the upperportion of the plate above openings 56, provides for inflow and outflowof convection currents of air induced to flow upwardlythru the space orflue 62, corresponding to flue 4'7 of Fig. 2. A manual switch 63 isindicated for controlling the current supply. Motor 64, impeller 66, andheating element 67, are arranged substantially the same as thecorresponding elements shown in Figs. 1 and 2.

In Figs. 5 and 6 in which the invention is applied to a portable type ofheater, the formation of the air flow casing for the air impeller, andthe conduit for delivering air to the same, are somewhat modified. Thusin this case the heater housing '71 is formed of substantially parallelupright rear and forward walls '72 and '73 which have their upperportions merging to form a curved top wall '74. The sides or ends of thehousing are formed by upright end walls '76. Suitable supporting legs7'7 are provided to retain the housing in spaced relationship with thefloor, and the bottom wall '78 of the housing is perforated to permitupward flow of air currents. Air flow casing '79, corresponding tocasing 22 of Figs. 1 and 2, surrounds the rotatable impeller 81, and hasa forwardly directed or curved discharge portion 82 communicating withan upper row of apertures 83 in front wall '73. Casing '79 is alsoprovided with inflow openings 83 and 84. A certain amount of the airdrawn in thru opening 83 can flow directly from the exterior thruopenings 86 in front wall '73, and a certain amount of the air flowingthru opening 83 can be taken from the air flow occurring upwardly thruperforated bottom wall '78. Conduit 8'7, corresponding to conduit 33 ofFigs. 1 and2, extends 89 for flow of convection currents of air. Thelower end of this flue is in communication with the exterior of thehousing thru openings in bottom wall 78, while the upper end of the flueisin communication with the exterior of the housing' thru a row ofopenings'fl; immediately, above openings 83. g 1

That form of the invention illustrated in Fig. 7 is somewhat similar tothat described above with reference to Figs. 1 and 2, in that it is alsoan air heater of the wall recess type. Utilizing the same designatingnumerals for the housing, it will be noted that the motor 93 is mountedupon the back wall 11 of housing 10. The impeller 94 is similarlydisposed within an air flow casing 96 and is mounted upon the shaft ofmotor 93. Inflow of air into casing 96 is effected solely thru opening97 surrounding motor 93, and this opening communicates with conduit 98corresponding to conduit 33 of'Figs. 1 and 2. The medial part of grille99 is imperforate; upper, lower and side openings being provided forinflow and outflow of currents of air. Shell 101 surrounding motor 93 isflared to efficiently deliver air drawn into conduit 98 to the impeller94. Wall 102 of conduit 98 is preferably extended upwardly behind thedischarge portion 103 of casing 96, thus forming an upwardly forwardlysloped wall 104. By means of this construction two spaced walls aredisposed between all parts of the heating elements and the back wall 11.In fact it is preferable to form conduit 98 as a part of a metal shellwhich entirely surrounds casing 96 and which has separate vertical sidewalls spaced inwardly from the side walls of the housing. The space orupstanding flue 106, between walls 102, 104 and back wall 11, can be incommunication with the inflow side of casing 96 thru an annular opening107 surrounding motor 93.

With an electrical air heater of the types described above it isdesirable to provide some means for manually controlling the directionof discharge of heated air. Thus in Fig. 7 there is shown a curved vane108, which is mounted within the discharge portion 102 of housing 96 bya suitable hinged connection 109. A handle 111 is secured to this vaneand projects thru one of the openings in the front grille. Bymanipulating handle 111 vane 108 can be set at different angles, as forexample the limiting position shown in dotted lines, or any intermediateposition. Thus the angle of discharge of the hot air with respect to thehorizontal, can be adjusted to suit convenience of particularconditions.

The circuit diagram illustrated in Fig. 8 can be utilized with any ofthe electrical air heaters previously described. In this case the fan orblower motor is indicated at 112, and the electrical heating means isdivided into three elements 113, 114, and 115. Manual control switch 117is provided with three terminals or contacts marked 1, 2, 3 and 4.Current supply line L1 is shown connected to terminal 4, while currentsupply line L2 is shown connected to one side of motor 112, and thecommon terminals of the elements 113, 114 and 115. A fuse 118 is shownconnected in series with line L2. This fuse can be of such a characteras to open the circuit when the temperature is increased beyond a givenmaximum, and is mounted at some convenient point within the heaterhousing. In the event of occurrence of abnormal condition, as forexample disruption of the fan or blower motor while the heating elementsare operating at full capacity, fuse element 118 will open the circuitbefore a fire hazard is created. The other terminals of elements 113,114 and 115 are connected to the contacts of switch 117 as shown and theother.

side of motor 112 is connected to contact 2. Switch 117 is provided witha manual control element having high, medium, low and off posi- .tions.

In high position of the switch, contacts 1, 2, 3-and 4 are shuntedtogether so that motor 112 is connected across lines L1 and La andwhereby all of the heating elements are connected together in parallel.In medium position of switch 117 contact 3 is disconnected from contact4, but contacts 1, 3 and 4 are shunted. Thus motor 112 continues tooperate, but only elements 113 and 114 are connected in parallel acrossthe current supply line. For low position of switch 117, contacts 2 and3 are disconnected from contact 4 and line L1 and only contact 1 isshunted with contact 4. Therefore only element 113 is in operation andfan motor 112 is disconnected. In this position of the switch all of theheat developed by element 113 is imparted to convection currents of airwhich are induced to circulate thru the heater housing, without theaccelerating effect of the fan. For off position of the switch 112 allof the element and motor 112 are disconnected from the current supplylines.

In the circuit connection shown in Fig. 9 the electrical heating meansis divided into four elements 113, 114, 115 and 116. Elements 115 and116 are always shunted together in the manner indicated. Substantiallythe same connections are made between these elements and the contacts ofswitch 117, and with the current supply lines L1 and La. Howevertemperature responsive fuse 118 is omitted, and a temperature responsiveor thermostat control switch 121 has its contacts 122 and 123 interposedin series with line La. Preferably switch 121 is mounted within theheating housing in the path of currents of air being drawn from the roominto the heater, as for example as indicated in Fig. 2. When in suchposition it operates responsive to the temperature of the air within theroom being heated. Manual operation of switch 117 to its differentoperating positions, is substantially the same as has been previouslydescribed with respect to Fig. 8. How ever if in any one position of theswitch, the temperature of the air within the room rises to apredetermined value, depending upon the setting of switch 121, thecontacts of this switch automatically open to interrupt further supplyof current both to the heating elements and to the fan motor 112. Whenthe temperature of the air within the room drops down below a givenpredetermined value, the contacts 122 and 123 are automatically closed,to reestablish operation of the heater. For low position of switch 117,it will be noted that switch 121 only controls the supply of current toelement 113 and not to the fan motor 112.

The circuit diagram of Fig. 10 differs from that described with respectto Fig. 9 in that another temperature responsive switch 124 is utilizedin addition to switch 121. Likewise in this instance one side of fan 112is connected directly to line L: rather than in series with the contactsof switch 121. Common terminals of elements 113 and 115 are connected toone of the contacts of 4 switch 121, while the corresponding terminal ofelements 115 is connected to one of the contacts of switch 124. Theother contact of switch 124- is connected to line La.

only controls supply .gf current to element 113. Switch 124 ispreferably adjusted so that its con- Switch 124 therefore tacts willautomatically open when the temperature of the air 'of the room is at acertain value,

. continue to increase to a somewhat higher temperature value, switch121 will openjlits contacts to discontinue supply of current to elements114' and 115. As the temperature of the room falls, contacts of' switch121 will first be established, to again supply current to elements 114and 115. If the temperature continues to fall, the contact to switch 124will be closed to also supply current to element 113. It is obvious thatthis mode of operation will tend to maintain a more constant temperatureof the air within a room. The same modeof operation will take place formedium position of switch 117. For low position of switch 117, fan 112is disconnected, and only element 113 is supplied with current, but thesupply of current is under the control of switch 124.

I claim:

1. In an electrical air heater, a housing, walls within said housingserving to divide the interior thereof into primary and secondaryupwardly extending air passages, electrical heating means disposedwithin the housing and adapted to heat air in said primary passage, anda fan or blower disposed within the housing and adapted to effect arapid flow of air into the housing, thru said primary passage, and outof the housing after being heated by said electrical means, saidsecondary passage being open to the exterior of the housing at its lowerand upper ends thereby forming a flue for upwardly circulatingconvection currents of air.

2. In an electrical air heater, a housing, walls disposed within saidhousing and serving to divide the interior thereof into primary andsecondary air flow passages, said housing having a back wall and saidsecondary passages being interposed between said' back wall and saidprimary passage, an electrical fan disposed within the housing andserving to cause a rapid flow of air into the housing, thru said primarypassage, and out of the housing, and electrical means serving to heatthe air flowing thru said primary passage, said housing having spacedupper and lower openings serving to permit flow of convection currentsof air into the housing, thru said secondary passage, and out of thehousing.

3. In an electrical air heater, a housing. an electrical fan disposedwithin the housing, an air flow casing surrounding the impeller of thefan, said casing having air inflowopenings communicating with theexterior of the housing and having a discharge portion spaced upwardlyfrom said inflow opening. and adapted to discharge air laterally of thehousing, and'electricalheating means disposed within said casing, saidcasing being so disposed within the housing as to form a secondary fluefor flow of convection currents of air thru the housing. 1

4. electrical air heater, a housing, an electrical motor disposed withinthe housing, a

rotatable air impeller driven by the motor, an

air flow casing surroundingsaidimpeller, said casing having a relativelywide discharge portion opening thru one side wall of the housing abovesaid impeller, said casing also having inflow openings communicatingwith ,the exterior of the-housing at points spaced below said dischargeportion.

5. In an electrical air-heater, a housing, an electrical motor disposedwithin the housing, a rotatable impeller mounted upon the shaft of .themotor, an upright air flow casing disposed within the housing andsurrounding said impeller, and electrical heating means disposed withinsaid casing, said casing having a relatively wide discharge portionopening thru one side wall of the housing, and having inflow openingscommunicating with the exterior of the housing at points spaced belowsaid discharge portion.

6. In an electrical air heater, a housing having upright front and backwalls an electrical motor disposed within the housing, a rotatable airimpeller mounted upon the shaft of the motor, a casing disposed withinthe housing and 'surroundingsaid impeller, said casing being immediatelybehind said front wall and spaced from said back wall, electricalheating means disposed within said casing, said casing having adischarge portion communicating thru said front walls and having inflowopenings communicating through said front wall below said dischargeportion, said wall being substantially imperforate, a motor 115 disposedwithin .said housing, a rotatable air impeller mounted upon the shaft ofthe motor, 'a casing surrounding said impeller and diposed immediatelybehind said front wall, said casing being spaced forwardly from saidback wall. and electrical heating means disposed within said casing, theupper part of said casing serving to. form a discharge portion to directheated air laterally thru said front wall, said casing also havinginflow openings communicating -thru said front wall in an area spacedbelow such discharge portion.

8. In an electrical air heater, a housing having relatively uprightfront and back-walls, a motor mounted within the housing, an airimpeller mounted upon the shaft to the motor, an air flow casingsurrounding said impeller, said casing having an upper .dischargeportion and an opening below said discharge portion for the inflow ofair to the impeller, said front wall having openings adapted tocommunicate with said discharge portion and other openings at asubstantial distance below serving to communicate with the inflowopenings in the casing, electrical heating means within the casing andmeans disposed 1. .3 within the housing, embracing the lower portion ofsaid casing, and forming an inflow conduit, said conduit communicatingwith the inflow openings in said casing and also communicating with theexterior of the atmosphere thru openings in 14,; said front wall.

, 9. In an electrical air heater adapted to be positioned within a wallrecess, a housing having a relatively upright back wall, and having a.grille for'ming-a-front wall for the same, an electrical motor disposedwithin the housing with its shaft horizontal, a rotatable air impellermounted upon the horizontal shaft of the motor, an upright air flowcasing surrounding said impeller and mounted immediately behind saidgrille, said casing being spaced with respect to the back, top, bottomand side walls of the housing, and electrical heating means disposed insaid casing, said casing having a discharge portion communicating thruan upper portion of the grille and an inflow portion communicatingthrough a lower portion of the grille, said space between said casingand the back, top and bottom and side walls of said housing forming anupwardly extending flue for convection currents of air and communicatingwith the exterior of the housing thru the upper and lower edges of saidgrille.

10. In an electrical air heater, a housing adapted to be fitted into awall recess and comprising relatively upright back and side walls, abottom wall and a top wall, and a grille extending over the front of thehousing, a motor mounted within the housing with its shaft horizontal, arotatable air impeller mounted upon the shaft to the motor, an air flowcasing surrounding said impeller and having a diverging dischargeportion adapted to discharge air laterally thru an upper portion of thegrille, said casing also having inflow openings, an inflow conduitformed immedi-' ately below said casing and having one portion thereofcommunicating with the exterior of the housing thru said grille andanother portion thereof communicating with said inflow openings of saidcasing, and electrical heating means associated with said casing, bothsaid casing and said conduit being spaced from the back, sides, bottomand top walls of said housing thereby forming a relatively upright fluefor convection currents of air, said flue being in communication at itsupper and lower ends with the exterior of the housing thru said grille.

11. In an electrical air heater, a housing, an electrical motor disposedwithin the housing, a rotatable air impeller driven by the motor, anupright air flow casing within the housing and surrounding saidimpeller, said casing having a relatively wide discharge portion openingthrough one side wall of the housing, said casing also having inflowopenings communicating with the exterior of the housing at points spacedfrom said discharge portion and adjacent the axis of rotation of saidair impeller, and an electric heating element surrounding the peripheryof said air impeller, whereby a forced draft of air is caused to passinto and out of said housing past said heating element.

12. In an electrical air heater, a housing, an electrical motor disposedwithin the housing, a rotatable air impeller driven by the motor, an airflow casing surrounding said impeller, said casing having a relativelywide discharge portion opening through one side wall of the housing,said casing also having inflow openings communicating with the exteriorof the housing at points spaced from said discharge portion and adjacentthe axis of rotation of said air impeller, an electric heating elementsurrounding the periphery of said air impeller, whereby a forced draftof air is caused to pass into and out of said housing past said heatingelement, and a second air flow casing spaced from and surrounding saidfirst air flow casing to provide a path for convection currents ofheated air.

13. In an electrical heater, an upright housing having an upright backwall and also a grille forming an upright front wall for the same, anelectrical motor disposed within the housing with its shaft arrangedhorizontally, a rotatable impeller mounted upon said shaft, an uprightair flow casing having its lower portion surrounding the impeller andmounted immediately behind said grille, said casing being" spaced withrespect to the back, top and bottom walls of the housing, the rear wallof the casing being upright and having its upper portion slopedforwardly, the lower portion of the casing having communication throughthe grille for inflow of air to the impeller and the upper portion ofthe casing having communication thru the grille for the forwarddischarge of heated air, the contour of the casing as viewed from thefront of the housing being of reduced width for the lower portionsurrounding the impeller and of enlarged width for the upper portion ofthe casing from which ARTHUR J. KERCHER.

